Most if not all electronic products benefit from increasing including functions and performance in integrated circuit chips particularly in a smaller (or at least not larger) overall physical size or form factor. These needs for more, faster, and smaller are often very visible with the many consumer electronic products including but not limited to personal portable devices such as cellular phones, digital cameras, and music players.
The demands for smaller yet higher performing semiconductor devices have motivated the development of new techniques for producing smaller and less expensive semiconductor devices. One of these technologies involves packaging the integrated circuit chip in as small a form factor as possible in addition to manufacturing the integrated circuit chip as efficiently as possible.
Usually, many individual devices are constructed on a semiconductor wafer. When the devices are separated into individual rectangular units, each takes the form of an integrated circuit chip. In order to interface a chip with other circuitry, it is common to mount it with leads and individually connect pads on the chip to the leads of a package using extremely fine wires or similar electrical connectors. The assemblies are then packaged by individually encapsulating them in molded plastic or ceramic bodies.
Integrated circuit packaging technology has shown an increase in the number of chips mounted on a single circuit board or substrate that parallels the reduction in the number of components needed for a circuit. This results in packaging designs that are more compact, in the physical size and shape of a device, and provide a significant increase in overall integrated circuit density. However, integrated circuit density continues to be limited by the area available for mounting chips on a substrate.
To condense the packaging of individual devices, packages have been developed in which the integrated circuit package is not much larger than the integrated circuit(s) within. Each package site is a structure that provides mechanical support for the individual integrated circuit device(s). The package also provides one or more layers of interconnect lines that enable the devices to be connected electrically to surrounding circuitry.
In some cases, multi-chip devices can be fabricated faster and more cheaply than a corresponding single integrated circuit chip, that incorporates all the same functions. Some multi-chip modules have been found to increase circuit density and miniaturization, improve signal propagation speed, reduce overall device size, improve performance, and lower costs.
However, such multi-chip modules can be bulky. Package density is determined by the area required to mount a chip or module on a circuit board. One method for reducing the board size of multi-chip modules and thereby increase their effective density is to stack the chips vertically within the module or package. Such designs are improvements over prior packages that combined several chips and associated passive components side by side in a single, horizontal layer.
In any case, electrical connections and the leads can be very closely spaced even with a single integrated circuit chip. The close spacing of the electrical connections results in several problems in manufacturing as well as assembly of the integrated circuit package and the circuit board. One such problem involves a lack of space to supply a ground level voltage to the integrated circuit chip(s). This is particularly critical as the integrated circuit chip(s) cannot operate without a ground level voltage supply.
Despite the advantages of recent developments in semiconductor fabrication and packaging techniques, there is a continuing need for improving integrated circuit package form factors, numbers of integrated circuit package signal connections, and integrated circuit connections to a ground level supply.
Thus, a need still remains for an integrated circuit package system to provide improved compactness, functions, efficiency, and performance. In view of the increasing demand for improved density of integrated circuits and particularly portable electronic products, it is increasingly critical that answers be found to these problems.
Solutions to these problems have been long sought but prior developments have not taught or suggested any solutions and, thus, solutions to these problems have long eluded those skilled in the art.